The present invention relates generally to medical methods, devices, and systems. In particular, the present invention relates to methods, devices, and systems for the endovascular, percutaneous or minimally invasive surgical treatment of bodily tissues, such as tissue approximation or valve repair. More particularly, the present invention relates to repair of valves of the heart and venous valves.
Surgical repair of bodily tissues often involves tissue approximation and fastening of such tissues in the approximated arrangement. When repairing valves, tissue approximation includes coapting the leaflets of the valves in a therapeutic arrangement which may then be maintained by fastening or fixing the leaflets. Such coaptation can be used to treat regurgitation which most commonly occurs in the mitral valve.
Mitral valve regurgitation is characterized by retrograde flow from the left ventricle of a heart through an incompetent mitral valve into the left atrium. During a normal cycle of heart contraction (systole), the mitral valve acts as a check valve to prevent flow of oxygenated blood back into the left atrium. In this way, the oxygenated blood is pumped into the aorta through the aortic valve. Regurgitation of the valve can significantly decrease the pumping efficiency of the heart, placing the patient at risk of severe, progressive heart failure.
Mitral valve regurgitation can result from a number of different medical defects in the mitral valve or the left ventricular wall. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, the papillary muscles or the left ventricular wall may be damaged or otherwise dysfunctional. Commonly, the valve annulus may be damaged, dilated, or weakened limiting the ability of the mitral valve to close adequately against the high pressures of the left ventricle.
The most common treatments for mitral valve regurgitation rely on valve replacement or repair including leaflet and annulus remodeling, the latter generally referred to as valve annuloplasty. A recent technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the “bow-tie” or “edge-to-edge” technique. While all these techniques can be very effective, they usually rely on open heart surgery where the patient's chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated high mortality and morbidity.
Consequently, alternative and additional methods, devices, and systems for performing the repair of mitral and other cardiac valves have been developed. Such methods, devices, and systems preferably do not require open chest access and are capable of being performed either endovascularly, i.e., using devices which are advanced to the heart from a point in the patient's vasculature remote from the heart, or by other minimally invasive approach.
One such technique involves plicating a valve leaflet so as to shorten a free edge of the leaflet. This shortening permits a better coaptation between opposing leaflets. One such technique is described in U.S. Publication 20160038149, where two U shaped hooks or clips, rotatable in relation to each other, are used to plicate a leaflet in a minimally invasive transcatheter technique.
The foregoing technique has been carried forward into a product known as the MitraClamp® by Heartworks LLC. FIGS. 1-3 show images of a device 20 that follows the MitraClamp concept. This device comprises two “U” shaped clips, a first clip 21, and a second clip 22 extending in the same direction. The first clip 21 comprises a first 24 and a second 26 downwardly descending prong which are connected to each other at an upper end by a first bridge 28. The second clip 22 comprises a third 30 and a fourth 32 downwardly descending prong, which are connected to each other at an upper end by a second bridge 34. At least one annular collar 36 is attached to the first prong 24 of the first clip 22. The third downwardly descending prong 30 passes through the collar 36 and is rotatable within the collar. This rotation allows the device 20 to assume a number of different conditions, some of which are exemplified in FIGS. 1, 2, and 3, as the second clip 22 rotates about an axis running up through the third prong 30 of the second clip 22.
The MitraClamp in operation may be envisaged with reference to FIGS. 1A, 2A, and 3A. These figures show how a free edge 50 of a leaflet of a valve in a patient's heart may be shortened in its free length by using the device 20. The figures show how the device may be positioned in relation to the free edge 50 of a leaflet in FIG. 1A, by inserting the device in the condition shown in FIG. 1 over a generally linearly extending free edge of a leaflet in a patient's heart, by known means. Once the device is introduced in this condition, the second clip 22 may be slowly rotated (by known means) around the axis of the third prong 30. In FIG. 2A, this rotation is indicated by the arrow R1 after the second clip 22 has been rotated 180 degrees. At this stage, the free edge 50 of the leaflet has not been plicated and is still in its starting condition shown in FIG. 1A. Then, the second clip is rotated a further 180 degrees as shown by arrow R2 in FIG. 3A. This final movement pulls the free edge 50 of the leaflet back towards the second prong 26 of the first clip 21, thereby folding (or plicating) the free edge of the leaflet 50 so that its net length is reduced. More specifically, two points A and B on the free edge of the leaflet are indicated in FIGS. 1A, 2A, and 3A. Before the plication, points A and B are a distance D1 apart from each other in the direction of the free edge 50 (FIG. 1A). After the plication, the points A and B are a much smaller distance D2 apart from each other in the direction of the free edge (FIG. 3A). When this condition has been achieved, the two clips are locked in relation to each other so that further movement is not possible. To achieve this locked result, an overhanging clasp 38 may be provided on bridge 28. The bridge 34 of the second clip 22 may be shaped to fit into the overhang of the clasp. The two clips are then fixed against linear movement in relation to each other (by known means). The delivery mechanism (not shown) may then be removed, and the clips 21, 22 are left behind in the heart of the patient, affixed to the free edge 50 of the leaflet which now has a reduced length. This result provides a better coaptation between the shortened leaflet and an opposing leaflet (not shown).
The device in the prior art as thus described still has many shortcomings. For, even when the leaflet has been plicated using this device, it may be found that the coaptation of the leaflets is not greatly improved because the device 20 itself prevents the two leaflets from forming an effective seal against each other during systole. Another problem is that the size of the device may be found to be inappropriate for the size of the leaflets when the device is positioned against the leaflets. At this stage of the procedure, it may be too late for the physician to withdraw the device and replace it with another differently sized device. Yet another problem is that the “U” shape of the clips in the device may render the device too large diametrically for easy delivery into the heart.
Therefore, devices, systems and methods are desired which may address the problems found in the art. At least some of these objectives will be met by the embodiments described herein below.